Spider mites serious problem in peanuts

After the hot, droughty summer, peanuts in North Carolina and Virginia developed a serious problem with spider mites in August and into September.

“Spider mites have been a real problem here,” says David Jordan, North Carolina State University Extension peanut specialist. “We expect them in dry weather, and they have been pretty widespread. They feed on foliage and can cause leaves to shed off.”

Farmers have turned to chemical control, but it is not a quick fix. “You don't get 100 percent control since spider mites are down in the canopy and sometimes underneath the leaf itself,” says Jordan. “Also, it is relatively expensive.”

This year, there were also some difficulties because distributors don't keep on hand a lot of the two chemicals — Danitol and Comite. “It was a bit of a challenge getting the chemicals where they needed to be, but I think the farmers that wanted it were able to obtain it.”

Farmers had to ask themselves whether or not a particular field would still make a crop if it got some adequate rainfall soon, says Rick Brandenburg, Extension entomologist. “If the answer was ‘not very likely,’ then the value of a spider mite spray may be in question. If the field still had potential and there was some rain in sight, then it may be worth the investment.”

Controlling mites usually requires two applications about three to five days apart, he says. “Treating one time often will not stop a spider mite problem because Comite or Danitol will not kill the eggs. Unless it rains, mites almost certainly will come back with a vengeance in a couple of weeks.”

In a two-spray strategy, the first gets the mites, and the second gets all the mites that have hatched from the eggs present during the first spray, he says.

“Mites love hot and dry weather, and they have had a summer to remember,” says Brandenburg.

The Tar Heel peanut crop doesn't look very good, Jordan says. “It's been such a dry year. The crop is really spotty. Much of it has been dry the last couple of weeks (to Sept. 7), and the foreseeable future doesn't look real good.”

The growth and maturity have been held back, he says. “This crop will probably mature later, but farmers who don't have many nuts on the vine may decide there is not much reason to wait on harvesting.”

Jordan estimated that the statewide yield would be about 2,700 pounds per acre, down from 3,100 pounds the year before. A yield that low would mark the end of a good run. “For several years, we have been averaging over 3,000 pounds per acre.”

One odd note about this season: “We haven't seen a tremendous amount of incidences of symptoms of tomato spotted wilt,” says Jordan. “But it may be there and disguised by the effects of the drought.”

Bob Sutter, chief executive officer of the North Carolina Peanut Growers Association, thinks the crop will be average to below average in North Carolina, with a yield close to 2,800 pounds.

The crop varied widely with some farmers looking at good crops and some at poor ones, he said.

There was some relief from the drought late in August, when quite a few farmers got some rain and their peanuts started growing again. That means some cooperation will be needed from the weather in the fall.

“If you got rain, you are hoping now that the first frost will be late this fall so your crop will have a chance to get set and matured,” says Sutter. “If we can get through October without a frost, most of our growers probably will be okay.”

There seemed to be no rain in sight at the beginning of September and the better crops were going down fast.

There should nevertheless be sufficient supply to meet the demand for North Carolina peanuts, Sutter says. “The buyers will have the opportunity to find what they need, but not necessarily from the farmers they contracted with.”

In Virginia at the beginning of September, peanut plants were finally closing most of the rows and were adding a late crop, says Joel Faircloth, Virginia Tech Extension cotton and peanut specialist.

That was good news, he says, because the drought took care of the early crop. “What we make will be the late part. That being said, the rain has ceased again for the past 10 days and peanuts are again showing signs of drought stress. Digging will start in the third week of September, as things look right now, and maybe a little earlier in places.”

A lot of the diseases normally expected had not shown up by early September. “We haven't seen sclerotinia except in the cool snaps,” Faircloth says. “That is good because it is frequently a very expensive disease to control.

“Also, we haven't seen much CBR, but it could still come in. We don't have much to control it with.”

The peanut- and cotton-growing areas of southeastern Virginia got some much-needed rains late in August.

“Peanuts probably benefited more from the August rains than the cotton since it only takes 25 days to put on a peanut pod,” Faircloth says. “I am not sure what the yield will be but it will probably start with a two. I am hoping we reach 2,700 pounds per acre. There is very little of the crop that I would characterize as excellent.”